Surgical instrument with stamped double-flange jaws

ABSTRACT

A surgical instrument includes an elongated shaft having a distal portion and a proximal portion coupled to a housing. An inner shaft member extends at least partially through the elongated shaft and is selectively movable in a longitudinal direction. An end effector is supported by the distal portion of the elongated shaft. The end effector includes upper and lower jaw members pivotally coupled to the distal portion of the elongated shaft about a pivot axis and including a pair of laterally spaced flanges. The pairs of flanges of the jaw members are arranged in an offset configuration such that one flange of the upper jaw member is positioned on a laterally exterior side of a corresponding flange of the lower jaw member, and the other flange of the upper jaw member is positioned on a laterally interior side of the other flange of the lower jaw member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 15/013,096 filed Feb. 2, 2016, which is adivisional application of U.S. patent application Ser. No. 13/461,335filed May 1, 2012, now U.S. Pat. No. 9,820,765, the entire contents ofeach of which are incorporated herein by reference.

BACKGROUND 1. Technical Field

The present disclosure relates generally to the field of surgicalinstruments. In particular, the disclosure relates to an endoscopicelectrosurgical forceps that is economical to manufacture and is capableof sealing and cutting relatively large tissue structures.

2. Background of Related Art

Instruments such as electrosurgical forceps are commonly used in openand endoscopic surgical procedures to coagulate, cauterize and sealtissue. Such forceps typically include a pair of jaws that can becontrolled by a surgeon to grasp targeted tissue, such as, e.g., a bloodvessel. The jaws may be approximated to apply a mechanical clampingforce to the tissue, and are associated with at least one electrode topermit the delivery of electrosurgical energy to the tissue. Thecombination of the mechanical clamping force and the electrosurgicalenergy has been demonstrated to join adjacent layers of tissue capturedbetween the jaws. When the adjacent layers of tissue include the wallsof a blood vessel, sealing the tissue may result in hemostasis, whichmay facilitate the transection of the sealed tissue. A detaileddiscussion of the use of an electrosurgical forceps may be found in U.S.Pat. No. 7,255,697 to Dycus et al.

A bipolar electrosurgical forceps typically includes opposed electrodesdisposed on clamping faces of the jaws. The electrodes are charged toopposite electrical potentials such that an electrosurgical current maybe selectively transferred through tissue grasped between theelectrodes. To effect a proper seal, particularly in relatively largevessels, two predominant mechanical parameters must be accuratelycontrolled; the pressure applied to the vessel, and the gap distanceestablished between the electrodes.

Both the pressure and gap distance influence the effectiveness of theresultant tissue seal. If an adequate gap distance is not maintained,there is a possibility that the opposed electrodes will contact oneanother, which may cause a short circuit and prevent energy from beingtransferred through the tissue. Also, if too low a force is applied thetissue may have a tendency to move before an adequate seal can begenerated. The thickness of a typical effective tissue seal is optimallybetween about 0.001 and about 0.006 inches. Below this range, the sealmay shred or tear and above this range the vessel walls may not beeffectively joined. Closure pressures for sealing large tissuestructures preferably fall within the range of about 3 kg/cm2 to about16 kg/cm2.

As is traditional, the term “distal” refers herein to an end of theapparatus that is farther from an operator, and the term “proximal”refers herein to the end of the electrosurgical forceps that is closerto the operator.

SUMMARY

The present disclosure relates to an electrosurgical apparatus andmethods for performing electrosurgical procedures. More particularly,the present disclosure relates to electrosurgically sealing tissue.

The present disclosure describes a surgical instrument for treatingtissue that is economical to manufacture and is capable of sealing andcutting relatively large tissue structures.

The surgical instrument includes an elongated shaft having a distalportion and a proximal portion coupled to a housing. The elongated shaftdefines a longitudinal axis. An inner shaft member extends at leastpartially through the elongated shaft. The inner shaft member isselectively movable in a longitudinal direction with respect to theelongated shaft. An end effector adapted for treating tissue issupported by the distal portion of the elongated shaft. The end effectorincludes upper and lower jaw members pivotally coupled to the distalportion of the elongated shaft about a pivot axis. The upper and lowerjaw members include a first and second pair of laterally spaced flanges,respectively. The first and second pairs of flanges of the jaw membersare arranged in an offset configuration such that one flange of theupper jaw member is positioned on a laterally exterior side of acorresponding flange of the lower jaw member, and the other flange ofthe upper jaw member is positioned on a laterally interior side of theother flange of the lower jaw member.

Additionally or alternatively, the housing includes a movable actuatingmechanism configured to cause longitudinal movement of the inner shaftmember relative to the elongated shaft.

Additionally or alternatively, the elongated shaft includes at least onefeature formed therein configured to operably engage the movableactuating mechanism.

Additionally or alternatively, the elongated shaft has a generallycircular profile joined along two opposing longitudinal edges.

Additionally or alternatively, the two opposing longitudinal edges arelaser welded together.

Additionally or alternatively, the two opposing longitudinal edges arejoined by one of a box joint interface and a dovetail joint interface.

Additionally or alternatively, the surgical instrument includes a campin supported by the inner shaft member such that longitudinal movementof the inner shaft member is imparted to the cam pin.

Additionally or alternatively, each of the first and second laterallyspaced flanges define a camming slot for engaging the cam pin.

Additionally or alternatively, the upper and lower jaw members areconstructed as substantially identical components positioned in alaterally offset manner with respect to one another.

Additionally or alternatively, the pivot axis extends through each ofthe flanges in a direction substantially transverse to the longitudinalaxis.

Additionally or alternatively, the inner shaft member extends throughthe jaw members on a laterally interior side of each of the flanges.

Additionally or alternatively, the surgical instrument includes a knifeselectively movable in a longitudinal direction with respect to theinner shaft member.

Additionally or alternatively, the inner shaft member includes a knifeguide disposed on a distal end of the inner shaft member such that theknife is substantially surrounded on four lateral sides.

According to another aspect of the present disclosure, a surgicalinstrument is provided. The surgical instrument includes an elongatedshaft including a distal portion and a proximal portion coupled to ahousing. The elongated shaft defines a longitudinal axis. An endeffector adapted for treating tissue is supported by the distal portionof the elongated shaft. The end effector includes first and second jawmembers pivotally coupled to one another to move between open and closedconfigurations. Each of the jaw members includes a pair of laterallyspaced flanges. Each of the flanges includes a camming surface. A knifeextends at least partially through the elongated shaft and isselectively movable in a longitudinal direction between the flanges ofthe jaw members. A blade of the knife is extendable into a tissuecontacting portion of the jaw members. An inner shaft member extends atleast partially through the elongated shaft and is selectively movablein a longitudinal direction with respect to the knife and with respectto the elongated shaft. The inner shaft member carries a cam pinpositioned to engage the camming surface of each of the flanges toinduce the jaw members to move between the open and closedconfigurations.

Additionally or alternatively, the elongated shaft includes at least onefeature defined therein configured to engage a movable actuatingmechanism operably associated with the housing.

Additionally or alternatively, the laterally spaced flanges of the jawmembers are arranged in a nestled configuration wherein both of theflanges of one of the jaw members are arranged within a laterallyinterior side of the laterally spaced flanges of the other of the jawmembers.

According to another aspect of the present disclosure, a method ofmanufacturing a surgical device including a housing and an elongatedshaft for coupling an end effector with the housing of the surgicaldevice is provided. The method includes the steps of stamping at leastone feature into a blank of sheet metal and folding the blank into suchthat two opposing longitudinal edges of the blank meet at a longitudinalseam to form an elongated shaft. The method also includes the step ofoperably coupling an end effector to at least one feature formed at adistal portion of the elongated shaft. The method also includes the stepof engaging at least one actuating mechanism supported by a housing withat least one feature formed at a proximal portion of the elongated shaftto operably couple the proximal portion of the elongated shaft with thehousing. The actuating mechanism is configured to selectively move theend effector between an open position and a closed position.

Additionally or alternatively, the method includes the step of joiningthe two opposing longitudinal edges along the longitudinal seam.

Additionally or alternatively, the joining step further comprises laserwelding the longitudinal seam. The longitudinal seam may be a box jointconfiguration or a dovetail joint configuration.

Additionally or alternatively, the method includes the step of couplinga drive rod to the at least one actuating mechanism at a proximal endand to the end effector at a distal end. The drive rod may be configuredto translate within and relative to the elongated shaft upon movement ofthe at least one actuation mechanism to effect actuation of the endeffector.

Additionally or alternatively, the method includes the step of stampingat least one feature at a distal end of the blank such that a clevis isformed at a distal end of the elongated shaft. The clevis may beconfigured to support the end effector.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the presentdisclosure and, together with the detailed description of theembodiments given below, serve to explain the principles of thedisclosure.

FIG. 1 is a perspective view of an electrosurgical forceps according toan embodiment of the present disclosure including a housing, anelongated shaft, and an end effector;

FIG. 2A is an enlarged perspective view of the end effector of FIG. 1depicted with a pair of jaw members in an open configuration;

FIG. 2B is an enlarged perspective view of the end effector of FIG. 1depicted with the pair of jaw members in a closed configuration;

FIG. 3A is a perspective view of the end effector and elongated shaft ofFIG. 1 with parts separated;

FIG. 3B is an enlarged perspective view of a distal portion of theelectrosurgical forceps of FIG. 1 depicting a distal knife guide coupledto an inner shaft member;

FIG. 4 is a proximally-facing perspective view of a rotation knobdepicting a cavity for receiving the elongated shaft of FIG. 1;

FIG. 5 is a cross-sectional, perspective view of the end effectorassembled with the elongated shaft of FIG. 1;

FIG. 6 is a partial, perspective view of a distal portion of a jawactuation mechanism of the end effector of FIG. 1;

FIG. 7 is a partial, perspective view of distal portion of a knifeactuation mechanism of the end effector of FIG. 1;

FIG. 8 is a perspective view of a lower jaw member of the end effectorof FIG. 1 depicting a double flag at a proximal end thereof;

FIG. 9 is a cross-sectional, perspective view of the lower jaw member ofFIG. 8;

FIG. 10 is a schematic view of the nestled arrangement of the doubleflag of FIG. 8 with a double flag of an upper jaw member;

FIG. 11 is a schematic view of an alternative offset arrangement ofdouble flags of an alternate pair of jaw members;

FIG. 12 is a perspective view of a proximal portion of the instrument ofFIG. 1 with a portion of the housing removed revealing internalcomponents;

FIG. 13 is a partial, side view of a proximal portion of the jawactuation mechanism of FIG. 6 depicting a connection between the jawactuation mechanism and the jaw drive rod mechanism for impartinglongitudinal movement to the jaw drive rod;

FIG. 14A is a perspective view of a proximal portion of the knifeactuation mechanism of the end effector of FIG. 1;

FIG. 14B is a cross-sectional, top view of a knife collar of the knifeactuation mechanism of the end effector of FIG. 1;

FIG. 15A is a side view of the proximal portion of the instrument ofFIG. 12 depicting a movable handle in a separated position with respectto a stationary handle, which corresponds to the open configuration ofthe end effector depicted in FIG. 2A, and a knife trigger in a separatedconfiguration with respect to the stationary handle, which correspondsto an un-actuated or proximal configuration of a knife with respect tothe jaw members;

FIG. 15B is a side view of the proximal portion of the instrument ofFIG. 12 depicting the movable handle in an intermediate position withrespect to the stationary handle, which corresponds to a first closedconfiguration of the end effector wherein the jaw members encounter oneanother;

FIG. 15C is a side view of the proximal portion of the instrument ofFIG. 12 depicting the movable handle in an approximated configurationwith respect to the stationary handle, which corresponds to a secondclosed configuration of the end effector wherein the jaw members applyan appropriate pressure to generate a tissue seal; and

FIG. 15D is a side view of the proximal portion of the instrument ofFIG. 12 depicting the knife trigger in an actuated configuration, whichcorresponds to an actuated or distal position of the knife with respectto the jaw members.

DETAILED DESCRIPTION

Referring initially to FIG. 1, an embodiment of an electrosurgicalforceps 400 generally includes a housing 412 that supports variousactuators thereon for remotely controlling an end effector 414 throughan elongated shaft 416. Although this configuration is typicallyassociated with instruments for use in laparoscopic or endoscopicsurgical procedures, various aspects of the present disclosure may bepracticed with traditional open instruments and in connection withendoluminal procedures as well.

The housing 412 is constructed of a left housing half 412 a and a righthousing half 412 b. The left and right designation of the housing halves412 a, 412 b refer to the respective directions as perceived by anoperator using the forceps 400. The housing halves 412 a, 412 b may beconstructed of sturdy plastic, and may be joined to one another byadhesives, ultrasonic welding or other suitable assembly methods.

To mechanically control the end effector 414, the housing 412 supports astationary handle 420, a movable handle 422, a trigger 426 and arotation knob 428. The movable handle 422 is operable to move the endeffector 414 between an open configuration (FIG. 2A) wherein a pair ofopposed jaw members 430, 432 are disposed in spaced relation relative toone another, and a closed or clamping configuration (FIG. 2B) whereinthe jaw members 430, 432 are closer together. Approximation of themovable handle 422 with the stationary handle 420 serves to move the endeffector 414 to the closed configuration and separation of the movablehandle 422 from the stationary handle 420 serves to move the endeffector 414 to the open configuration. The trigger 426 is operable toextend and retract a knife blade 456 (see FIGS. 2A and 2B) through theend effector 414 when the end effector 414 is in the closedconfiguration. The rotation knob 428 serves to rotate the elongatedshaft 416 and the end effector 414 about a longitudinal axis A-Aextending through the forceps.

To electrically control the end effector 414, the housing 412 supports aswitch 436 thereon, which is operable by the user to initiate andterminate the delivery of electrosurgical energy to the end effector414. The switch 436 is in electrical communication with a source ofelectrosurgical energy such as electrosurgical generator 443 or abattery (not shown) supported within the housing 412. The generator 443may include devices such as the LIGASURE® Vessel Sealing Generator andthe Force Triad® Generator as sold by Covidien Energy-based Devices ofBoulder, Colo. A cable 442 extends between the housing 412 and thegenerator 443 and may include a connector (not shown) thereon such thatthe forceps 400 may be selectively coupled and decoupled electricallyfrom the generator 443.

Referring now to FIGS. 2A-3, the end effector 414 may be moved from theopen configuration (FIG. 2A) wherein tissue (not shown) is receivedbetween the jaw members 430, 432, and the closed configuration (FIG.2B), wherein the tissue is clamped and sealed. Upper jaw member 430 andlower jaw member 432 are mechanically coupled to the elongated shaft 416about a pivot pin 444. The upper and lower jaw members 430, 432 areelectrically coupled to cable 442, and thus to the generator 443 (e.g.,via a respective wire extending through the elongated shaft 416) toprovide an electrical pathway to a pair of electrically conductive,tissue-engaging sealing plates 448, 450 disposed on the lower and upperjaw members 432, 430, respectively. A pair of wire conduits 478 a and478 b may be provided to guide wires proximally from the end effector414. The wire conduits 478 a and 478 b may be constructed of a plastictube, and serve to protect wires from sharp edges that may form onsurrounding components. The sealing plate 448 of the lower jaw member432 opposes the sealing plate 450 of the upper jaw member 430, and, insome embodiments, the sealing plates 448 and 450 are electricallycoupled to opposite terminals, e.g., positive or active (+) and negativeor return (−) terminals associated with the generator 443. Thus, bipolarenergy may be provided through the sealing plates 448 and 450.Alternatively, the sealing plates 448 and 450 and/or the end effector414 may be configured for delivering monopolar energy to the tissue. Ina monopolar configuration, the one or both sealing plates 448 and 450deliver electrosurgical energy from an active terminal, e.g. (+), whilea return pad (not shown) is placed generally on a patient and provides areturn path to the opposite terminal, e.g. (−), of the generator 443.

The jaw members 430, 432 may be pivoted about the pivot pin 444 to movethe end effector 414 to the closed configuration of FIG. 2B wherein thesealing plates 448, 450 provide a pressure to tissue graspedtherebetween. In some embodiments, to provide an effective seal, apressure within a range between about 3 kg/cm² to about 16 kg/cm² and,desirably, within a working range of 7 kg/cm² to 13 kg/cm² is applied tothe tissue. Also, in the closed configuration, a separation or gapdistance “G” may be maintained between the sealing plates 448, 450 by anarray of stop members 454 (FIG. 2A) disposed on or adjacent the sealingplates 448, 450. The stop members 454 contact opposing surfaces on theopposing jaw member 430, 432 and prohibit further approximation of thesealing plates 448, 450. In some embodiments, to provide an effectivetissue seal, an appropriate gap distance of about 0.001 inches to about0.010 inches and, desirably, between about 0.002 and about 0.005 inchesmay be provided. In some embodiments, the stop members 454 areconstructed of an electrically non-conductive plastic or other materialmolded onto the jaw members 430, 432, e.g., by a process such asovermolding or injection molding. In other embodiments, the stop members454 are constructed of a heat-resistant ceramic deposited onto the jawmembers 430, 432. Other methods of controlling gap are contemplatedincluding those described in the commonly assigned patent applicationentitled GAP CONTROL VIA OVERMOLD TEETH AND HARD STOPS (application Ser.No. 13/835,004 filed Mar. 15, 2013, now U.S. Pat. No. 8,939,975).

Electrosurgical energy may be delivered to the tissue through theelectrically conductive seal plates 448, 450 to effect a tissue seal.Once a tissue seal is established, a knife blade 456 may be advancedthrough a knife channel 458 defined in one or both jaw members 430, 432to transect the sealed tissue. Knife blade 456 is depicted in FIG. 2A asextending from the elongated shaft 416 when the end effector 414 is inan open configuration. In some embodiments, a knife lockout is providedto prevent extension of the knife blade 456 into the knife channel 458when the end effector 414 is in the open configuration, thus preventingaccidental or premature transection of tissue and avoiding safetyconcerns.

Referring now to FIG. 3A, the elongated shaft 416 includes variouslongitudinal components that operatively couple the end effector 414 tothe various actuators supported by the housing 412 (FIG. 1). An outershaft member 460 defines an exterior surface of the elongated shaft 416and supports movement of other components therethrough as describedbelow. The outer shaft member 460 may be constructed from a flat stockpiece of metal. In constructing the outer shaft member 460, a stamping,punching or similar metal-working process may be employed to initiallygenerate a flat blank that includes an appropriate outer profile and anyinterior openings or features. Thereafter, the necessary bends andcurves may be formed by bending the flat blank with a press brake, orother suitable metal-working equipment. The outer shaft member 460 maybe formed by folding the flat blank into a generally circular profile(or generally rectangular profile) such that two opposing longitudinaledges of the flat blank meet at a longitudinal seam (not explicitlyshown). Although the longitudinal seam does not necessarily requirejoining by a mechanical interlock or any other suitable process, theseam may, in some embodiments, be joined by laser welding (or othersuitable process) to form a continuous circular or other geometric(e.g., rectangular) profile. The seam may be generally straight, oralternatively, a box joint, a dovetail joint, or any other suitableinterface known in the metal-working arts.

The outer shaft member 460 defines a clevis 464 at a distal end thereoffor receiving the jaw members 430 and 432. Opposing vertical sidewalls464 a and 464 b of the outer shaft member 460 include respective bores466 a, 466 b extending therethrough to frictionally support the pivotpin 444 and maintain an orientation of the pivot pin 444 with respect tothe outer shaft member 460. Alternatively or additionally, the pivot pin444 may be fastened to the outer shaft member 460 by a laser orheat-based welding, adhesives, chemical bonding, or other suitablemanufacturing processes.

At a proximal portion of the outer shaft member 460, various featuresare provided that serve to couple the outer shaft member 460 to variouselements of the housing 412. More specifically, the proximal portion ofthe outer shaft member 460 includes, in order from distal to proximal, aseries of tabs 486 extending therefrom, a washer 499 extending aroundouter shaft member 460, a pair of opposing longitudinal slots 468 a, 468b defined therethrough and provided to allow longitudinal translation ofa dowel pin 493 therethrough, and a longitudinal slot 469 extendingdistally from a proximal end thereof to couple the outer shaft member460 to the rotation knob 428. The connection established between theouter shaft member 460 and the rotation knob 428 is described below withreference to FIG. 4. As shown in FIGS. 15A-15D, the series of tabs 486and the washer 499 serve to aid in securing the proximal portion of theouter shaft member 460 within the housing 412.

The pivot pin 444 extends through a proximal portion of each of the jawmembers 430, 432 to pivotally support the jaw members 430, 432 at thedistal end of the outer shaft member 460. With reference to FIG. 8, aproximal portion of each of the jaw members 430, 432 is configured as a“double flag.” The double flag configuration refers to the two laterallyspaced parallel flanges or “flags” 430 a, 430 b and 432 a, 432 brespectively, extending proximally from a distal portion of the jawmembers 430 and 432. A lateral cam slot 430 c and a lateral pivot bore430 d extend through each of the flags 430 a, 430 b of the upper jawmember 430. Similarly, a lateral cam slot 432 c and a lateral pivot bore432 d extend through each of the flags 432 a, 432 b of the lower jawmember 432. The pivot bores 430 d, 432 d receive the pivot pin 444 in aslip-fit relation that permits the jaw members 430, 432 to pivot aboutthe pivot pin 444 to move the end effector 414 between the open andclosed configurations (FIGS. 2A and 2B, respectively).

An inner shaft member 480 is received within the outer shaft member 460and is configured for longitudinal motion with respect to the outershaft member 460. A distal knife guide 498 includes sidewalls 482 a, 482b and a proximal key slot 487 that supports a key member 494therethrough. During assembly of electrosurgical forceps 400, the distalknife guide 498 is slid proximally within a distal end of the innershaft member 480, such that the inner shaft member 480 surrounds aportion of the distal knife guide 498, and opposing lateral sides of thekey member 494 align with and fit within opposing longitudinal key slots495 a, 495 b defined through the inner shaft member 480 to couple theknife guide 498 to the inner shaft member 480 (FIG. 3B). The inner shaftmember 480 includes a pair of opposing longitudinal slots 472 a, 472 bextending proximally from a distal end of the inner shaft member 480along a portion of the inner shaft member 480 between the opposinglongitudinal key slots 495 a, 495 b. The longitudinal slots 472 a, 472 ballow the distal end of the inner shaft member 480 to aid in sliding ofthe distal knife guide 498 proximally within the inner shaft member 480.Once the key member 494 is aligned with and fit within the longitudinalkey slots 495 a, 495 b, the key member 494 effectively couples thedistal knife guide 498 to the inner shaft member 480, as depicted byFIG. 3B.

The sidewalls 482 a, 482 b define a longitudinal slot 483 through thedistal knife guide 498 that provides lateral support to the knife 402.The knife 402 is substantially surrounded at a distal end thereof by thedistal knife guide 498 on four lateral sides and the sidewalls 482 a,482 b of the distal knife guide 498 constrain side-to-side lateralmotion of the knife 402. Thus, the distal knife guide 498 serves to urgethe knife 402 into a central position within the elongated shaft 416,thereby ensuring proper alignment of the knife 402 as the knife 402reciprocates within knife channel 458 (FIG. 2A). The distal knife guide498 includes features for operatively coupling the inner shaft member480 to the end effector 414. A proximal portion 488 of the inner shaftmember 480 is configured for receipt within the housing 412 (FIG. 1),and includes features for operatively coupling the inner shaft member480 to the actuators supported thereon, e.g. the movable handle 422.

The distal knife guide 498 includes a through bore 490 extending throughthe sidewalls 482 a, 482 b for receiving the cam pin 492. Distally ofthe through bore 490, a longitudinal slot 496 is defined through thesidewalls 482 a, 482 b. The longitudinal slot 496 provides clearance forthe pivot pin 444, and thus, permits longitudinal reciprocation of theinner shaft member 480 independent of the pivot pin 444.

The proximal portion 488 of the inner shaft member 480 includes, inorder from distal to proximal, a pair of opposing longitudinal knifeslots 488 a, 488 b extending therethrough, a pair of opposing distallocking slots 481 a, 481 b extending therethrough, a pair of opposingproximal locking slots 471 a, 471 b extending therethrough, and aproximal end 491 configured to engage a suitable mechanical interfacewithin the housing 412 to aid in proper support of the inner shaftmember 480 within the housing 412 (see FIGS. 12 and 15A-15D).

The knife 402 is a generally flat, metal component defining a profilethat may be constructed by a stamping process. The knife 402 supportsthe sharpened knife blade 456 at a distal-most end thereof. The sharpedge of the knife blade 456 may be applied to the distal end of theknife 402 subsequent to the stamping process that forms the profile. Forexample, various manufacturing techniques may be employed such asgrinding, coining, electrochemical etching, electropolishing, or othersuitable manufacturing processes, for forming sharpened edges. Alongitudinal slot 406 is defined within the knife 402 to provideclearance for the pivot pin 444, the cam pin 492, and the key member494. A proximal through bore 408 a extends through a proximal portion408 of the knife 402 and provides a mechanism for operatively couplingthe knife 402 to the trigger 426 via the dowel pin 493. The connectionbetween the knife 402 and the trigger 426 is described in detail belowwith reference to FIGS. 12, 13, 14A, and 14B.

Referring now to FIG. 4, the rotation knob 428 includes a passageway 429defined therethrough for receiving the outer shaft member 460. Thepassageway 429 has a generally circular profile corresponding to thecircular profile of the outer shaft member 460. The passageway 429includes a longitudinal keying member 414 that is configured to alignwith and be seated within longitudinal slot 469 (FIG. 3A) of the outershaft member 460. The keying member 414 projects laterally inward alongthe length of passageway 429 such that the insertion of the proximal endof the outer shaft member 460 into the passageway 429 of the rotationknob 428 operatively couples the outer shaft member 460 to the rotationknob 428 and, thus, permits longitudinal motion of the inner shaftmember 480 therethrough.

In one embodiment, a cable clearance passageway (not shown) is definedthrough rotation knob 428 to permit passage of electrical cables orwires that electrically couple the sealing plates 448, 450 to theelectrosurgical generator 443 (FIG. 1). Rotational motion imparted tothe rotation knob 428 may thus impart rotational motion to each of thecomponents of the elongated shaft 416, and to the end effector 414,which is coupled thereto.

As shown in FIG. 13, the rotation knob 428 is seated within an interiorcompartment 434 of the housing 412 and, as shown in FIG. 1, extendslaterally outward from opposing sides of the housing 412 (only shownextending laterally outward from housing half 412 b). The interiorcompartment 434 defines distal and proximal passageways 434 a and 434 bthat permit the passage of the components of the elongated shaft 416therethrough. The rotational motion of the rotation knob 428 may belimited by a stop boss 418 projecting distally from the rotation knob428 (FIG. 4). The stop boss 418 is positioned to engage the distalpassage 434 a of the compartment 434 to restrict rotational motion ofthe rotation knob 428. For example, in some embodiments, the stop boss418 may engage the distal passage 434 a to restrict rotational motion ofthe rotation knob 428 to180 degrees in either direction.

Referring now to FIG. 5, the end effector 414 is coupled to the distalend of the elongated shaft 416 by the pivot pin 444. The pivot pin 444is coupled to the sidewalls 464 a and 464 b of the clevis 464 defined atthe distal end of the outer shaft member 460. Thus, the pivot pin 444represents a longitudinally stationary reference for the longitudinalmovements of inner shaft member 480 and the knife 402. Laterally inwardof the sidewalls 464 a, 464 b, the pivot pin 444 extends through theflags 432 a, 432 b of the lower jaw member 432, the flags 430 a and 430b of the upper jaw member 430, the sidewalls 482 a, 482 b of the knifeguide 498, and the knife 402. The jaw members 430, 432 are free to pivotabout the pivot pin 444, and the inner shaft member 480 and the knife402 are free to translate longitudinally around the pivot pin 444.

Referring now to FIG. 6, the end effector 414 is shown in the openconfiguration. Since the knife guide 498 is coupled to the cam pin 492,when the inner shaft member 480 is in the distal position, the cam pin492 is located in a distal position in cam slots 430 c and 432 c definedthrough the flags 430 a, 430 b, 432 a, 432 b of the jaw members 430,432, respectively.

The inner shaft member 480 may be drawn proximally relative to the pivotpin 444 to move the end effector 414 to the closed configuration (seeFIG. 2B). Since the longitudinal position of the pivot pin 444 is fixed(by the outer shaft member 460, which is removed from view in FIG. 6 forclarity), and since the cam slots 430 c, 432 c are obliquely arrangedwith respect to the longitudinal axis A-A, proximal retraction of thecam pin 492 through the cam slots 430 c, 432 c induces the jaw members430, 432 to pivot toward one another about the pivot pin 444.Conversely, when the end effector 414 is in the closed configuration,longitudinal translation of the inner shaft member 480 in a distaldirection induces the jaw members 430, 432 to pivot away from oneanother toward the open configuration.

Referring now to FIG. 7, the longitudinal slot 406 in the knife 402extends around both the pivot pin 444 and the cam pin 492, and thus thepins 444, 492 do not interfere with the reciprocal motion of the knife402. The pivot pin 444 and cam pin 492 extend through the slot 406 insuch a manner as to guide longitudinal motion of the knife 402 as wellas constrain vertical motion of the knife 402. The blade 456 at thedistal-most end of the knife 402 is centrally aligned by the knife guide498, as discussed hereinabove. Properly aligned, the blade 456 readilyenters the knife channel 458 defined in the jaw members 430, 432.

Referring now to FIGS. 8 and 9, the lower jaw member 432 is constructedof three major components. These components include a double-flag jawinsert 440, an insulator 442 and the sealing plate 448. The flags 432 a,432 b of the jaw member 432 define a proximal portion of the double-flagjaw insert 440, and a generally u-shaped channel 444 extends distally tosupport the tissue engaging portion of the jaw member 432. Thedouble-flag jaw insert 440 includes various planar surfaces, and may beconstructed as a sheet metal component formed by a stamping process. Insuch a stamping process, the cam slots 432 c and pivot holes 432 d maybe punched into a flat blank, and subsequently the blank may be bent toform the flags 432 a, 432 b and the u-shaped channel 444.

The insulator 442 may be constructed of an electrically insulativeplastic such as a polyphthalamide (PPA) (e.g., Amodel®), polycarbonate(PC), acrylonitrile butadiene styrene (ABS), a blend of PC and ABS,nylon, ceramic, etc. The electrically insulative plastic may beovermolded onto the jaw insert 440 in a single-shot injection moldingprocess such that sealing plate 448 is overmolded to the jaw insert 440.Additionally or alternatively, the electrically insulative plastic maybe mechanically coupled to the jaw insert 440, e.g., pressed, snapped,glued, etc. Various features may be molded into the insulator 442 thatfacilitate the attachment of the sealing plate 448 to the insert 440.For example, tabs may be provided that permit a snap-fit attachment ofthe sealing plate 448, or ridges may formed that permit ultrasonicwelding of the sealing plate 448 onto the insulator 442. The sealingplate 448 may be constructed of an electrically conductive metal, andmay be stamped from a flat sheet stock.

Referring now to FIG. 10, the flags 430 a, 430 b of the upper jaw member430 are depicted schematically in a nestled configuration with respectto the flags 432 a, 432 b of the lower jaw member 432. The proximalportion of the upper jaw member 430 is narrower than the proximalportion of the lower jaw member 432, and thus, a lateral spacing “S”between the flags 432 a, 432 b is sufficient to permit the flags 430 aand 430 b to be positioned therebetween. A pivot axis “P₀” extendsthrough an overlapping portion of the flags 430 a, 432 a, and 430 b, 432a such that the upper and lower jaw members 430, 432 may pivot about thecommon axis “P₀.” In the nestled configuration, the proximal portions ofthe upper and lower jaw members 430, 432 also share a common centerline“CL−1” that is transverse with respect to the pivot axis “P₀.”

An alternative to the nestled configuration illustrated in FIG. 10 isthe offset configuration illustrated schematically in FIG. 11. Aproximal portion of double-flag upper jaw member 450 includes flags 450a and 450 b. A proximal portion of a double-flag lower jaw member 452includes flags 452 a and 452 b and exhibits a width that is identical toa width of the proximal portion of the upper jaw member 450. To providean overlapping portion of the flags 450 a, 452 a and 450 b, 452 b suchthat the jaw members 450, 452 may pivot about the common axis “P₀,” oneflag 450 a of the upper jaw member 450 is positioned on a laterallyexterior side of the corresponding flag 452 a of the lower jaw member452, and the other flag 450 b of the upper jaw member 450 is positionedon a laterally interior side of the corresponding flag 452 b of thelower jaw member 452. In the offset configuration, a centerline “CL−2”of the proximal portion of the upper jaw member 450 is laterally offsetwith respect to a centerline “CL−3” of the lower jaw member 452.

Referring now to FIG. 12, the connection of the movable handle 422 andthe knife trigger 426 to the longitudinally movable components of theelongated shaft 416 is described. The movable handle 422 may bemanipulated to impart longitudinal motion to the inner shaft member 480,and the knife trigger 426 may be manipulated to impart longitudinalmotion to the knife 402. As discussed above, longitudinal motion of theinner shaft member 480 serves to move the end effector 414 between theopen configuration of FIG. 2A and the closed configuration of FIG. 2B,and longitudinal motion of the knife 402 serves to move knife blade 456through knife channel 458 (FIG. 2A).

The movable handle 422 is operatively coupled to the inner shaft member480 by a connection mechanism 476 (FIG. 12). The connection mechanism476 includes a clevis 478 defined at an upper end of the movable handle422. The clevis 478 is pivotally supported on the left housing half 412b by a pivot boss 479. A second complementary pivot boss (not shown) isprovided on the right housing half 412 a to support the clevis 478. Eachof two upper flanges 478 a and 478 b of the clevis 478 extend upwardlyabout opposing sides of a drive collar 484 supported on the inner shaftmember 480 and include rounded drive surfaces 497 a and 497 b thereon.Drive surface 497 a engages a proximal-facing surface of a distal lockcollar 484 a and drive surface 497 b engages a distal facing surface ofa proximal rim 484 b of the drive collar 484 (FIG. 13). The distal lockcollar 484 a engages the opposing distal locking slots 481 a, 481 b(FIG. 3A) extending through the proximal portion 488 of the inner shaftmember 480 to lock-fit the distal lock collar 484 a to the inner shaftmember 480. Thus, the distal lock collar 484 a is prevented fromlongitudinal motion relative to the inner shaft member 480. Drivesurface 497 a is arranged along the longitudinal axis A-A such thatpivotal motions of the movable handle 422 about the pivot bosses 479induce corresponding longitudinal motion of the drive collar 484 alongthe longitudinal axis A-A in the proximal direction. Drive surface 497 bis arranged along the longitudinal axis A-A such that pivotal motions ofthe movable handle 422 about the pivot bosses 479 induce correspondinglongitudinal motion of the distal lock collar 484 a along thelongitudinal axis A-A in the distal direction.

Referring now to FIG. 13, proximal longitudinal motion may be impartedto the inner shaft member 480 by pushing the proximal rim 484 b of thedrive collar 484 proximally with the movable handle 422 (FIG. 12) asindicated by arrow D4. The proximal rim 484 b engages a spring 489 thatis constrained between the proximal rim 484 b and a proximal lock collar415. The proximal lock collar 415 engages the opposing proximal lockingslots 471 a, 471 b (FIG. 3A) extending through the proximal portion 488of the inner shaft member 480 to lock-fit the proximal lock collar 415to the inner shaft member 480. Thus, the proximal lock collar 415 isprevented from longitudinal motion relative to the inner shaft member480 and serves as a proximal stop against which spring 489 compresses.

Distal longitudinal motion is imparted to the inner shaft member 480 bypushing the distal lock collar 484 a distally with drive surface 497 aof movable handle 422 as indicated by arrow D3 (FIG. 13). Distallongitudinal motion of the distal lock collar 484 a induces acorresponding distal motion of the inner shaft member 480 by virtue ofthe lock-fit coupling of the distal lock collar 484 a to the opposingproximal locking slots 471 a, 471 b extending through the proximalportion 488 of the inner shaft member 480 (FIG. 3A).

Proximal longitudinal motion of the inner shaft member 480 draws the campin 492 proximally to pivot the jaw members 430, 432 toward one anotherto move the end effector 414 to the closed configuration as describedabove with reference to FIG. 6. Once the jaw members 430 and 432 areclosed, the inner shaft member 480 essentially bottoms out (i.e.,further proximal movement of the inner shaft member 480 is prohibitedsince the jaw members 430, 432 contact one another). Further proximalmovement of the movable handle 422 (FIG. 12), however, will continue tomove the drive collar 484 proximally. This continued proximal movementof the drive collar 484 further compresses the spring 489 to impartadditional force to the inner shaft member 480, which results inadditional closure force applied to tissue grasped between the jawmembers 430, 432 (see FIG. 2B). The spring 489 also serves to bias themovable handle 422 to an open configuration such that the movable handle422 is separated from the stationary handle 420.

Referring again to FIG. 12, the trigger 426 is pivotally supported inthe housing 412 about a pivot boss 403 protruding from the trigger 426.The trigger 426 is operatively coupled to the knife 402 by a knifeconnection mechanism 404 such that pivotal motion of the trigger 426induces longitudinal motion of the knife 402. The knife connectionmechanism 404 includes upper flanges 426 a, 426 b of the trigger 426 anda knife collar 410.

Referring now to FIGS. 13, 14A, and 14B, the knife collar 410 includes acap member 411 coupled thereto and a pair of integrally formed pinbosses 439 a, 439 b extending from opposing sides thereof. The knifecollar 410 may include indentations or catches defined therein (notshown) that receive corresponding snap-in features (e.g., arms) of thecap member 411. The cap 411 may thus be assembled to the knife collar410 such that the cap 411 and the knife collar 410 translate together.As shown by FIG. 14B, the coupling of the knife collar 410 to the cap411 forms an interior circular channel 413 to capture the dowel pin 493therein such that the dowel pin 493 is supported on opposing endsbetween the knife collar 410 and the cap 411. The dowel pin 493 extendsthrough the proximal through bore 408 a extending through a proximalportion 408 of the knife 402 (FIG. 3A) to operably couple the knife 402to the knife collar 410. Upon longitudinal motion of the inner shaftmember 480, dowel pin 493 translates longitudinally within knife slots488 a, 488 b, respectively, of the inner shaft member 480 such that thelongitudinal motion of inner shaft member 480 is unimpeded by dowel pin493. Upon rotation of the elongated shaft 416 and end effector 414 aboutthe longitudinal axis A-A via the rotation knob 428 (FIG. 1), dowel pin493 freely rotates within the interior circular channel 413 such thatthe outer and inner shaft members 460 and 480 (removed from view in FIG.14B for clarity), the knife 402, and the dowel pin 493 rotate within theknife collar 410 about the longitudinal axis A-A. In this way, the knifecollar 410 serves as a stationary reference for the rotational movementof the outer shaft member 460, the inner shaft member 480, the knife402, and the dowel pin 493.

Referring again to FIG. 12, the upper flanges 426 a, 426 b of thetrigger 426 include respective slots 427 a, 427 b defined therethroughthat are configured to receive the pin bosses 439 a, 439 b,respectively, of the knife collar 410 such that pivotal motion of thetrigger 426 induces longitudinal motion of the knife collar 410 and,thus, the knife 402 by virtue of the coupling of knife 402 to the knifecollar 410 via the dowel pin 493 extending through the through bore 408a. During longitudinal motion of the knife collar 410, dowel pin 493translates longitudinally within the opposing slots 468 a, 468 b of theouter shaft member 460 and the slots 488 a, 488 b of the inner shaftmember 480.

Referring now to FIGS. 13 and 14A, when the trigger 426 is moved toinduce motion of the knife collar 410 in order to translate the blade456 through the knife channel 458, the knife collar 410 translates alongthe outer shaft member 460 in the direction of arrow A9 to abut a spring419 such that spring 419 compresses against a distal portion 421 of theinterior of the housing 412 (FIG. 12). The spring 419 biases the knifecollar 410 in a proximal direction to a proximal position along theouter shaft member 460.

Referring now to FIGS. 15A, 15B, 15C and 15D, a sequence of motions maybe initiated by moving the movable handle 422 to induce motion of thejaw drive mechanism in order to close the jaws 430, 432, and by movingthe trigger 426 to induce motion of the knife collar 410 in order totranslate the blade 456 through the knife channel 458. Initially, boththe moveable handle 422 and the knife trigger 426 are in a distal orun-actuated position as depicted in FIG. 15A. This arrangement of themoveable handle 422 and trigger 426 sustains the end effector 414 in theopen configuration (FIG. 2A) wherein the jaw members 430, 432 aresubstantially spaced from one another, and the knife blade 456 is in aretracted or proximal position with respect to the jaw members 430, 432.The initial distal position of the trigger 422 is actively maintained bythe influence of the spring 419 on the knife collar 410. The distalposition of the moveable handle 422, however, is only passivelymaintained, e.g., by internal friction within the jaw actuationmechanism. When both the moveable handle 422 and the knife trigger 426are in the distal, un-actuated position, pivotal motion of the knifetrigger 426 in a proximal direction, i.e., toward the stationary handle420, is prohibited by interference between the trigger 426 and moveablehandle 422. This interference prohibits advancement of the knife bladethrough the knife channel 458 when the end effector 414 is in the openconfiguration.

The movable handle 422 may be moved from the distal position of FIG. 15Ato the intermediate position depicted in FIG. 15B to move the jawmembers 430, 432 to the closed configuration (FIG. 2B). As the movablehandle 422 pivots about the pivot boss 479 in the direction of arrow M1(FIG. 15B), the drive surface 497 b of the movable handle 422 engagesthe proximal rim 484 b of the drive collar 484. The drive collar 484 andthe spring 489 are both driven proximally against the proximal lockcollar 415 and, thus, the inner shaft member 480 is driven proximally inthe direction of arrow M2 (FIG. 15B). As discussed above with referenceto FIG. 6, proximal movement of the inner shaft member 480 serves todraw the cam pin 492 proximally though the cam slots 430 c, 432 c of thejaw members 430, 432, respectively, and thus pivot the jaw members 430,432 toward one another. As the jaw members 430, 432 engage one anotherand no further pivotal movement of the jaw members 430, 432 may beachieved, the jaw actuation mechanism “bottoms out” and further proximalmovement of the cam pin 492 and the inner shaft member 480 is prevented.

The movable handle 422 may be moved from the intermediate position ofFIG. 15B to the actuated or proximal position of FIG. 15C to increasethe pressure applied by the jaw members 430, 432. As the movable handle422 pivots further about the pivot boss 479 in the direction of arrow M3(FIG. 15C), the drive surface 497 b presses the proximal rim 484 b ofthe drive collar 484 further distally against the spring 489 in thedirection of arrow M4 (FIG. 15C). The spring 489 is compressed againstthe proximal lock collar 415, and a tensile force is transmitted throughthe inner shaft member 480 to the jaw members 430, 432. The tensileforce supplied by the spring 489 ensures that the jaw members 430, 432apply an appropriate pressure to effect a tissue seal. When the movablehandle 422 is in the actuated or proximal position, electrosurgicalenergy may be selectively supplied to the end effector 414 to generate atissue seal.

When the movable handle 422 is in the actuated or proximal position, at-shaped latch 422 a extending proximally from an upper portion of themoveable handle 422 is received in a railway 420 a supported within thestationary handle 420. The railway 420 a serves to temporarily lock themovable handle 422 in the proximal position against the bias of thespring 489. Thus, the railway 420 a permits the maintenance of pressureat the end effector 414 without actively maintaining pressure on themovable handle 422. The flange 422 a may be released from the railway420 a by pivoting the movable handle 422 proximally and releasing themovable handle 422 to move under the influence of the spring 489.Operation of the railway 420 a is described in greater detail in U.S.patent application Ser. No. 11/595,194 to Hixson et al., now U.S. Pat.No. 7,766,910. In some embodiments (not shown), the latch 422 a and therailway 420 a may be eliminated to provide an instrument without thetemporary locking capability provided by these features.

When the movable handle 422 is in the actuated or proximal position, theknife trigger 426 may be selectively moved from the distal position ofFIG. 15C to the proximal position of FIG. 15D to advance the knife blade456 distally through knife channel 458. The knife trigger 426 may bepivoted in the direction of arrow M5 (FIG. 15D), about pivot boss 403 toadvance the flange 426 b of the knife trigger 426 distally in thedirection of arrow M6 such that the pin boss 439 b translates withinslot 427 b from the position shown in FIGS. 15A-15C to the positionshown in FIG. 15D. Although not explicitly shown in FIGS. 15A-15D, pinboss 439 a translates within slot 427 a in the same manner as describedabove with respect to pin boss 439 b and slot 427 b. Movement of flanges426 a, 426 b draws the knife collar 410 distally, which induces distallongitudinal motion of the knife 402 by virtue of the coupling of knife402 to the knife collar 410 via the dowel pin 493 extending through thethrough bore 408 a, as described above with reference to FIGS. 3A and14B.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely as examplesof particular embodiments. Those skilled in the art will envision othermodifications within the scope and spirit of the claims appended hereto.

Although the foregoing disclosure has been described in some detail byway of illustration and example, for purposes of clarity orunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the appended claims.

1-13. (canceled)
 14. A surgical instrument, comprising: an elongatedshaft extending from a housing and defining a longitudinal axis; an endeffector disposed at a distal end portion of the elongated shaft, theend effector including: a first jaw member including a first pair oflaterally spaced flanges, each of the first pair of laterally spacedflanges defining a cam slot; and a second jaw member including a secondpair of laterally spaced flanges disposed between the first pair oflaterally spaced flanges, each of the second pair of laterally spacedflanges defining a cam slot; a knife moveable along the longitudinalaxis to cut tissue disposed between the first and second jaw members;and a knife guide defining a longitudinal slot configured to receive theknife therethrough, the knife guide coupling the elongated shaft to theend effector, wherein movement of the elongated shaft along thelongitudinal axis causes corresponding movement of the knife guide alongthe longitudinal axis to move at least one of the jaw members relativeto the other jaw member.
 15. The surgical instrument according to claim14, wherein the knife guide is coupled to the end effector via a campin, the cam pin moveable within the cam slots defined by each of thefirst and second pairs of laterally spaced flanges.
 16. The surgicalinstrument according to claim 14, wherein movement of the elongatedshaft along the longitudinal axis moves a cam pin through a longitudinalslot defined by the knife and through the cam slots defined by each ofthe first and second pairs of laterally spaced flanges to move the endeffector between an open position and a closed position.
 17. Thesurgical instrument according to claim 14, wherein the first and secondjaw members are coupled to each other via a pivot pin configured to movethrough a longitudinal slot defined by the knife guide upon movement ofthe elongated shaft along the longitudinal axis.
 18. The surgicalinstrument according to claim 14, further comprising a knife triggeroperably coupled to the knife via a pin and configured to translate theknife along the longitudinal axis, the pin configured to move within alongitudinal slot defined by the elongated shaft upon movement of theelongated shaft along the longitudinal axis.
 19. The surgical instrumentaccording to claim 14, wherein the elongated shaft is disposed within anouter shaft member.
 20. A surgical instrument, comprising: an elongatedshaft extending from a housing and defining a longitudinal axis; an endeffector disposed at a distal end portion of the elongated shaft, theend effector including: a first jaw member including a first pair oflaterally spaced flanges, each of the first pair of laterally spacedflanges defining a cam slot; and a second jaw member including a secondpair of laterally spaced flanges disposed between the first pair oflaterally spaced flanges, each of the second pair of laterally spacedflanges defining a cam slot; a knife movable along the longitudinal axisto cut tissue disposed between the first and second jaw members, theknife defining a longitudinal slot; and a cam pin configured to bereceived through the cam slots defined by each of the first and secondpairs of laterally spaced flanges, wherein movement of the elongatedshaft along the longitudinal axis moves the cam pin through thelongitudinal slot defined by the knife and through the cam slots definedby each of the first and second pairs of laterally spaced flanges tomove the end effector between an open position and a closed position.21. The surgical instrument according to claim 20, further comprising aknife guide defining a longitudinal slot configured to receive the knifetherethrough, the knife guide coupling the elongated shaft to the endeffector, wherein movement of the elongated shaft along the longitudinalaxis causes corresponding movement of the knife guide along thelongitudinal axis to move at least one of the jaw members relative tothe other jaw member.
 22. The surgical instrument according to claim 21,wherein the knife guide is coupled to the end effector via a cam pin,the cam pin moveable within the cam slots defined by each of the firstand second pairs of laterally spaced flanges.
 23. The surgicalinstrument according to claim 20, wherein movement of the elongatedshaft along the longitudinal axis moves a cam pin through a longitudinalslot defined by the knife and through the cam slots defined by each ofthe first and second pairs of laterally spaced flanges to move the endeffector between an open position and a closed position.
 24. Thesurgical instrument according to claim 20, wherein the first and secondjaw members are coupled to each other via a pivot pin configured to movethrough a longitudinal slot defined by the knife guide upon movement ofthe elongated shaft along the longitudinal axis.
 25. The surgicalinstrument according to claim 20, further comprising a knife triggeroperably coupled to the knife via a pin and configured to translate theknife along the longitudinal axis, the pin configured to move within alongitudinal slot defined by the elongated shaft upon movement of theelongated shaft along the longitudinal axis.
 26. The surgical instrumentaccording to claim 20, wherein the elongated shaft is disposed within anouter shaft member.
 27. A surgical instrument, comprising: an elongatedshaft extending from a housing and defining a longitudinal axis; a pairof opposing jaw members disposed at a distal end portion of theelongated shaft; a knife moveable along the longitudinal axis to cuttissue disposed between the first and second jaw members; and a knifeguide defining a longitudinal slot configured to receive the knifetherethrough, the knife guide coupling the elongated shaft to the pairof opposing jaw members, wherein movement of the elongated shaft alongthe longitudinal axis causes corresponding movement of the knife guidealong the longitudinal axis to move at least one of the jaw membersrelative to the other jaw member.